Write drivers for inductive write heads of the magnetic disc drive are employed to provide write current to the head. These inductive heads record data on the magnetic media by selective reversal of magnetic flux caused by a reversal of the direction of current through the write head winding. The write current is reversed by a command from an input signal representing data to be recorded. However, the current reversal generates voltage differences across the head during the reversal period, thereby requiring the voltage to recover to a nominal level to again achieve a steady-state flow of current in the opposite direction after the reversal. The voltage fluctuations cause delay in achieving steady-state current conditions, and also cause overshoot or undershoot of the current waveform, either of which may cause "ringing".
Numerous techniques have been employed to address the problem of undershoot, ringing and delays in reaching steady-state conditions. The present invention is directed to an impedance matching circuit that matches the impedance of the write driver load, namely the impedance of the inductive head and the flex circuit connecting the head to the write driver.